1. Field of the Invention
Embodiments of the present invention generally relate to methods for operating a chemical vapor deposition chamber, and more specifically, methods for cleaning the chemical vapor deposition chamber.
2. Description of the Related Art
In the fabrication of integrated circuits and semiconductor devices, materials, such as oxides, are typically deposited on a substrate in a process chamber, such as a plasma-enhanced chemical vapor deposition (PECVD) chamber. The deposition processes often result in deposition of some of the materials on the walls, ceiling and components of the deposition chamber, changing the characteristics of the chamber and giving rise to particulate contamination. Further, since process gases are distributed through a gas distribution plate during processing, a layer of the materials is often formed on the gas distribution plate, which may clog the holes of the plate or flake off as particles that rain down on the substrate, thereby affecting the uniformity of deposition on the substrate and contaminating the substrate. Consequently, it is necessary to clean the interior of the deposition chamber on a regular basis.
Several methods of cleaning the deposition chamber have been developed. For example, a remote plasma cleaning procedure may be employed in which an etchant plasma is generated remote from the deposition chamber by a high density plasma source such as a microwave plasma system, toroidal plasma generator or similar device. Dissociated species from the etchant plasma are then transported to the deposition chamber where they can react with and etch away the undesired deposition build up. It is also common to remove the unwanted deposition material that builds up on the interior of chamber walls with an in situ cleaning procedure. Common in situ techniques include the use of an etchant gas, such as fluorine, to remove the deposited material from the chamber walls and other areas. The etchant gas is introduced into the chamber and plasma is formed so that the etchant gas reacts with and removes the deposited material from the chamber walls.
An in situ cleaning procedure generally provides a faster cleaning rate than the remote plasma cleaning procedure. However, an in situ cleaning procedure also causes more damage to the chamber hardware than the remote plasma cleaning procedure. For instance, one damage that typically occurs with in situ cleaning procedure is generally caused by the ion bombardment on the substrate support pedestal, which generates AlFx (since the support pedestal is generally made from AlN). AlFx in turn condenses on the cooler chamber components, such as the gas distribution plate, thereby generating particles and causing an accelerated drift of film properties.
Therefore, a need exists for an improved method for cleaning a PECVD chamber using the in situ cleaning procedure.